Refrigerant circulation



g- 1939- w. H. CARRIER REFRIGERANT CIRCULATION Filed April 8, 1936 [NIEN TOR. MAL/.5 f1 l a A T TORNE Y.

Patented Aug. 8, 1939 UNITED STATES 'PATE'NTOFFI nnmrenm'r CIRCULATIONWillis H. Carrier, Essex Fells, N.'J., assignor, by 'mesne assignments,to Carrier Corporation, Newark, N. J., a corporation of DelawareApplication April a, 1936, .Serial No. 73,219.

10 Claims. (01. 432-126) This invention relates to refrigeration. I Arefrigerating system, in general, includes three essential elements, anevaporator, a com- .pressor and a condenser. In operation, heat isabstracted from a medium in contact withthe evaporator by thevaporization of a volatile re- I irigerant therein. The resulting vaporis withrelatively high pressure are maintained...

In various types of conventional refrigerating systems, it is commonpractice to recirculate liquid refrigerant through the evaporator bymeans of a pump. This arrangement is very commonly used in evaporatorsof theshell andtube type.

Recirculation of refrigerant liquid-in this manner necessitates theprovision of a pump, a driving motor therefor, and a control for thedriving motor; and entails the supervision, maintenance, repair andreplacement of this equipmentl The general object of this invention istoprovide an improved method of and means for recirculating liquid throughan evaporator.

In practising the invention, advantage is taken of the pressuredifferential existing between the condenser and evaporator. Highpressure refrigerant being fed from the condenser to the evaporatorispassed throughan ejector nozzle and is caused to entrainrefrigerantdrawn from the sump of the evaporator. The refrigerant thus entrained ispassed 'to the refrigerant supply side of the evaporator without beingmechanically pumped thereto.

An object of the invention is to provide an improved refrigeratingsystem in which liquid passing from the condenser to the evaporatorentrains refrigerant liquid drawn from the sump of the evaporator andthus recirculates the lastmentioned refrigerant liquid through theevaporator.

Another object of the invention is to provide an improved refrigeratingsystem in which the quantity of refrigerant passed from the condenser tothe evaporator and the quantity of refrigerant recirculated through theevaporator are varied in accordance with the load on the system. j q

It is another object of the invention to provide a refrigerating systemwhich is relatively simple and inexpensive to construct and maintain,and which is entirely reliable in operation.

A feature of the invention resides in passing through an ejector nozzlehigh pressure refrigerant from the condenser of a refrigerating systemto entrain refrigerant drawnfrom the sump of the evaporator of thesystem .forrecirculation of said withdrawn refrigerantthrough-theevaporator. Y

A feature of the invention vision of a reservoir adapted to receive highpresresidesinthepm sure refrigerant liquidfrom a condenser, and an/"ejector in communication with the reservoir andin communication withthesump of an evaporator, refrigerant liquid from the reservoir and fromthe sump being supplied to the evaporator.

Another feature of the invention-resides in the provision of a reservoiradapted to receive high pressure refrigerant liquid from a condenser. anejector in communication with the'reservoir and in communication withthe sump of an evaporator, refrigerant liquid from the reservoir andfrom the sump being supplied to the evaporator,

. and means for controlling the action of the ejector in accordance withvariations in load on the evaporator.

A feature of the invention resides in the provision of a refrigeratingsystem including an ejector in the high pressure liquid line forwithdrawing refrigerant liquid from and recirculating it .through anevaporator, and an auxiliary line providing communication between thecondenser and evaporator, the line being controlled by a valveresponsive to variations in conditions of temperature and/or pressurewithin the evapo- 'rator.- This auxiliary line prevents freezing of thesump being supplied to the evaporator, and

Another feature of the invention resides in the pressure refrigerantliquid from a condenser, an ejector in communication with the reservoirand in communication with the sump of an evaporator, refrigerant liquidfrom the reservoir and from the sump being supplied to the evaporator, a

float valve in the reservoir for controlling the operation of theejector responsive to variations in the level of liquid in thereservoir, and means for damping oscillations of the float valve.

Other objects, features and advantages of the invention will be moreapparent-from the following description to be read in connection withthe accompanying drawing in which- Fig. 1 represents diagrammatically aportion of a refrigerating system embodying the invention; and

Fig. 2 is a sectional view illustrating applicants reservoir and ejectorapparatus on an enlarged scale.

Referring now to the drawing, 5 represents a condenser in whichrefrigerant is liquefied by a condensing medium flowing through pipes 6.Condensed refrigerant passes through pipe I to reservoir chamber 8.Chamber 8 is provided with adomed-portion 9 into which the refrigerantliquid is discharged. Projecting into the reservoir chamber 8 is anejector nozzle 9a. The outlet of nozzle 9a is positioned proximate theopening of pipe l0, which supplies refrigerant to perforated refrigerantdistributor plate I I of the evaporator l3. Fluid passed through pipesl2 of the evaporator I3 is cooled by the evaporation of refrigerant. Therefrigerant vapors are drawn off to a compressor (not shown) and arethen supplied in compressed condition to the condenser 5. Refrigerantfrom the distributor 'plate II which is not evaporated, passes to thesump H of the evaporator, which communicates through pipe I5 with theinlet to pipe I0. Within the domed section 9 of reservoir chamber 8 ispositioned a float l6 carried on and pivotally connected to a pair ofarms I1. Arms l1 are carried on pins l8 extending from a suitablesupport l9 within the reservoir chamber 8. Arms ll pivotally support aneedle valve 20' positioned proximate the throat of ejector nozzle 9aand adapted to control the flow of refrigerant liquid therethrough. V

In operation, high pressure refrigerant liquid passed to the reservoirchamber 8 through pipe '1 is forced through the ejector nozzle 9a andentrains liquid from pipe l5. Thus, there is passed through pipe in tothe distributing plate II a mixture of liquid refrigerant from thecondenser and liquid refrigerant from the sump of the evaporator. Inpractice it has been found that these are in the ratio of approximately1 to 4, or, in other words, that the quantity ofrefrigerant liquidpassingthrough pipe l0 approximates five times the quantity ofrefrigerant liquid passed through ejector nozzle So.

its will be understood, the level of refrigerant liquid in the highpressure side of the system varies in accordance with changes in heatload on the system. When theload decreases, the liquid level in. thedomed portion 9 of the reservoir falls. This results in a lowering ofthe float I6 and increased restriction of the throat of ejector nozzleSo by needle valve 20. Accordingly, less refrigerant passes through theejector nozzle 9a and less refrigerant-is drawn from pipe l5 by ejectoraction for recirculation when the load is low. Conversely, when there isan increase in heat load on the refrigerating system, the liquidcommodation for variations in load.

Preferably a ballle 2! is positioned in the reservoir chamber 0 in frontof the opening of pipe 1, to

. minimize disturbance within the reservoir chamber due to the admissionof refrigerant liquid and thus provide against unduly great oscillationof the float IS. A plate 22, carried on the float I6 is provided tostabilize operation of the float to prevent surging of refrigerant.

The dual arrangement of bars I! assures straight line motion of theneedle valve 20 in the center of nozzle 9a.

A pipe 23 provides communication between the evaporator" l3 and thecondenser 5. Pipe 23 enters the bottom of the condenser and enters theevaporator l3 above the normal refrigerant liquid level. Flow throughthe pipe is controlled by a valve 24 under the control of pressurestat25 disposed within the evaporator. Connection 23 serves two purposes.There is a tendency for refrigerant in a refrigerating system to returnto the condenser when the system has been shut down, leavinginsufficient liquid in the evaporator to be circulated over the tubes l2when operation is resumed. Hence, it is necessary to provide'some meansfor supplying liquid to the evaporator when operation is resumed.Moreover, it is desirable to provide against the freezing of liquidcirculated through the tubes I2. .Line 23, with its associated valve andpressurestat 25, serves in both of these capacities. When operation ofthe system is resumed after an interruption, the pressure in theevaporator becomes abnormally low. Pressurestat 25, responsive to theabnormally low pressure, opens valve 24. Since the liquid in thecondenser is at a pressure considerably higher than the pressure in theevaporator, refrigerant from the condenser is blown through pipe 23 tothe evaporator until normal operating conditions prevail. Since freezingoccurs when evaporator pressures are abnormally low, this arrangementalso prevents freezing of liquid in the tubes l2. If desired, thecontrol device designated 25 may constitute a thermostat instead of apressurestat as above described, such thermostat being arranged andadapted, in a manner well known in the art and therefore requiring nodetailed description herein, to open the valve 24 when the temperaturein the evaporator drops below a desired point. j To" prevent cavitation,the entire ejector nozzle is positioned below the level of liquidrefrigerant. While in the embodiment of the invention herein described,the float control is on the highpressure side of the refrigeratingsystem, a float control responsive to variations in the level of liquidrefrigerant on the low'side of the system may be used instead. It willbe understood that the refrigerant passing from the condenser and fromthe evap-.

Although valves of all types for controlling refrigerant flow throughnozzle 9a may be used and are deemed within-the purview hereof, needlevalves are to be preferred, since they reduce flow without reducing theenergy per weight unit of the primary refrigerant.

" Since many modifications may be made in the invention withoutdeparting from the scope thereof, it is intended that the foregoingdescription and the accompanying drawing shall be regarded asillustrative only, applicant limiting himself only as indicated in theaccompanying claims.

I claim:

1. A method of operating a refrigerating system including an evaporatorand a condenser, which consists in passing refrigerant from thecondenser to the evaporator through a first path, causing refrigerantpassed through said first path to entrain by ejector action otherrefrigerant withdrawn from the evaporator, whereby the other refrigerantis supplied to the evaporator with refrigerant passing from thecondenser, and passing refrigerant from the condenser to the evaporatorthrough a second path whenever the pressure in the evaporator dropsbelow a predetermined point.

2. A method of operating a refrigerating system including an evaporatorand a condenser, which consists in passing refrigerant from thecondenser to the evaporator through a first path, causing refrigerantpassed through said first path to entrain by ejector action otherrefrigerant withdrawn from the evaporator, whereby the other refrigerantis supplied to the evaporator with refrigerant passing from thecondenser, and passing refrigerant from the condenser to the evaporatorthrough a second path whenever the temperature in the evaporator dropsbelow a predetermined point.

3. In a refrigerating system, a condenser, an

, evaporator, an ejector, the primary intake of the ejector being incommunication with the condenser, the secondary intake of theejectorbeing ln communication with the evaporator, whereby primaryrefrigerant passing to the evaporator from the condenser through theejector will entrain secondary refrigerant withdrawn from theevaporator, and means in said ejector adapted to throttle the flow ofprimary refrigerant in accordance with variations in the level of liquidrefrigerant at a point in the system( 4. In a refrigerating systemincluding a condenser and an evaporator having a sump, means includingan ejector means for supplying to the evaporator refrigerant from thecondenser and refrigerant withdrawn from the sump of the evaporator, aneedle valve within the ejector, and means for varying the position ofthe needle valve in accordance with variations in the level ofrefrigerant liquid at a point in the system.

5. In a refrigerating system, a condenser, means forming a zone in whichrefrigerant is adapted to be evaporated an ejector, means providingcommunication between the primary intake of the ejector and thecondenser, means providing communication between the secondary intake ofthe ejector and the evaporator zone, whereby refrigerant passing to theevaporator refrigerant. supply means.

zone from the condenser through the ejector will entrain refrigerantwithdrawnfrom the evaporator zone, an auxiliary refrigerant liquidsupply conduit connecting said evaporator zone and said condenser in acourse bypassing said ejector, and means responsive to variations inevaporator zone operating conditions for controlling refrigerant fiowthrough said conduit in such manner that flow therethrough is permittedonly when refrigerant passing through the primary and secondary intakesof said ejector is insufiicient to satisfy the heat load on saidevaporator.

6. In a refrigerating system, a condenser, an

' evaporator, an ejector having a primary intake and a secondary intake,means providing communication between theprimary intake of the ejectorand the condenser, means providing communication between the secondaryintake of tlie ejector and the evaporator, whereby refrigerant passingto the evaporator from the condenser through the ejector will entrainrefrigerant withdrawn from the evaporator, a valve member positioned atsaid ejector and adapted to control refrigerant flow therethrough andmeans for varying the position of said valve member in accordance withvariations in the heat load on said evaporator. p

' 7. In a refrigerating system, a condenser, an evaporator, an ejectorhaving a primary intake and a secondary intake, means providingcommunication between the primary intake of the ejector and thecondenser, means providing communication between the secondary intake ofthe ejector and the evaporator, whereby refrigerant passing to theevaporator from the condenser through the ejector will entrainrefrigerant withdrawn from the evaporator, a needle valve memberadjustably poistioned within said ejectorand means for controlling thepoistion of said needle valve member in accordance with changes in heatload on said evaporator.

8. In a refrigerating system, a condenser, an evaporator, an'ejectorhaving a primary intake and a secondary intake, means providingcommunication between the primary intake of the ejector and thecondenser, means providing communication between the secondary intake ofthe ejector and evaporator, whereby refrigerant passing to theevaporator through the ejector will entrainrefrigerant withdrawn fromthe evaporator, a valve member positioned at said ejector and adapted tocontrol refrigerant flow therethrough, and means for varying theposition of said valve member in accordance with variations in the levelof liquid refrigerant at a point in the system. i

9. In a refrigerating system of the compression type including anevaporator, a compressor and a condenser, the combination of means forsupplying refrigerant under relatively high pressure from said condenserto said evaporator, means for utilizing the energy of said high pressurerefrigerant for effecting recirculation of refrigerant liquid throughsaid evaporator, and auxiliary supply means for supplying refrigerantliquid from said condenser to said evaporator in a course tioned means,said auxiliary refrigerant liquid supply means normally beinginoperative, and means for rendering operative said auxiliary supplymeans in response to demand for refrigerant liquid which is not met bysaid first-mentioned 10. In 'a refrigerating system, a condenser, meansforming a zone in' which refrigerant is adapted to be evaporated, anejector, means providing communication between the primary intake of theejector and the condenser, means providing communication between thesecondary intake of the ejector and the evaporator zone,.

whereby refrigerant passing to the evaporator zone from the condenserthrough the ejector will entrain refrigerant withdrawn from theevaporator zone, an auxiliary refrigerant liquid supply

